1. Field of the Invention
The present invention relates to a wireless communication apparatus and a wireless communicating method. More specifically, the present invention is directed to such a wireless communication apparatus equipped with a power consumption reducing function operable in the code division multiple access (CDMA) system, and also to a method for reducing power consumption of such a CDMA wireless communication apparatus.
2. Description of the Related Art
Generally speaking, wireless communication apparatuses such as a portable telephone and a mobile radio telephone employ batteries, or cells as compact power supplies with light weight. However, this sort of battery owns lifetime, namely continuously operable without recharging. As a consequence, in order to realize long communication time of this sort of wireless communication apparatus, power consumption thereof is necessarily reduced as much as possible.
Japanese Patent Application Laid-open No. Hei 9-200177 discloses one conventional CDMA receiver. Now, this conventional CDMA receiver will be described with reference to FIG. 1. A correlation filter used in the weighting process of the CDMA receiver shown in FIG. 1. This correlation filter is arranged by the delay circuit 100 and the weighting/synthesizing circuit 200. The delay circuit 100 outputs a plurality of tap output signals TP1 to TPn whose delay time is different from each other. This weighting/synthesizing circuit 200 executes the weighting process and synthesizing process operation based upon the outputs of this delay circuit 100, and then sends out the correlation output signal. This correlation output signal derived from the weighting/synthesizing circuit 200 is supplied to the timing control circuit 300. In response to the correlation output signal supplied from the weighting/synthesizing circuit 200, this timing control circuit 300 outputs the control signal so as to control the switch. The supply of the electric power from the power supply 500 to the weighting/synthesizing circuit 200 is ON/OFF-controlled by this switch control operation. That is, only within the section where the correlation peaks are concentrated, the switch element 4 is turned ON so that the supply of the electric power to the weighting/synthesizing circuit 200 is performed. Within such a section where the correlation peaks are not concentrated, no electric power is supplied to this circuit 200. As a result, since the electric power is supplied to the weighting/synthesizing circuit only in the necessary section, the power consumption is reduced.
Japanese Patent Application Laid-open No. Hei 9-261167 also describes the CDMA communication apparatus capable of reducing the power consumption. That is, this conventional CDMA communication apparatus contains the receiving unit operable in high speed for the communication channel, and also the receiving unit operable in low speed for the paging channel. Since the high speed process operation is required in the receiving unit for the communication channel, the resultant power consumption thereof is large. Therefore, in this conventional CDMA communication apparatus, the power supply of the paging channel receiving unit is turned ON during signal reception period, and the power supply of the communication channel receiving unit is turned OFF, so that the power consumption is reduced. Referring now to FIG. 2, this CDMA communication apparatus will be explained. As indicated in FIG. 2, the control unit 134 is provided with the mobile telephone. This control unit 134 ON/OFF-controls supplying of the electric power to the A/D converter 125, the reception filter 126, the correlator 127, and the spread code generating circuit 128 during the signal reception period. As a consequence, power consumption of the battery can be reduced during the signal reception period which is long.
On the other hand, in a wireless communication system such as a mobile communication apparatus, there are some possibilities that this communication apparatus employs a plurality of signal reception systems such as antennas and receiving circuits in order to avoid bad reception condition by the fading phenomenon. However, when a large number of antenna systems are employed, portability of this communication apparatus is deteriorated. Therefore, while only two signal reception systems are employed, such a reception system having a high reception level is generally selected to receive a signal. Such system is typically known as the antenna diversity technique.
However, since two signal reception systems are employed in one mobile communication apparatus and are simultaneously operated, this may cause the power consumption to be increased. Therefore, the power consumption is desirably reduced. However, the conventional communication apparatuses as described in the above-mentioned Japanese Patent Application Laid-open Nos. Hei 9-200177 and Hei 9-261167 have no effective power consumption reducing ideas.
An object of the present invention is to provide a wireless communication apparatus, and also a power consumption reducing method thereof, capable of effectively reducing power consumption.
Also, another object of the present invention is to provide a wireless communication apparatus, and also a power consumption reducing method thereof, in which at least two signal reception systems are provided and power consumption thereof can be effectively reduced.
To achieve the above-described objects of the present invention, a wireless communication apparatus of the present invention comprises a plurality of receivers for receiving signals to output reception signals and controller for substantially stopping operation of at least one of the plural receivers based upon the reception signals received by said receivers.
Also, to achieve the above-described objects of the present invention, a power consumption reducing method of a wireless communication apparatus comprises the steps of receiving signals at a plurality of reception systems to output a plurality of reception signals; and substantially stopping operation of at least one of the plural reception systems based upon the plurality of reception signals.
To achieve the above-described objects of the present invention, a CDMA communication apparatus comprises at least two antennas, at least two receiving circuits provided in correspondence with the antennas for demodulating signals received by said antennas to thereby output reception signals, at least two delayprofile circuits provided in correspondence with the receiving circuits for correlating said reception signals with respect to a predetermined data to thereby output correlation value data and a searcher circuit for detecting peaks from at least two correlation value data derived from the delayprofile circuits, wherein the searcher circuit includes first stopping means for comparing the peaks detected from the correlation value data with each other to obtain a comparison result and for substantially stopping operation of at least one of the plural receiving circuits based on the comparison result.
To achieve the above-described objects of the present invention, a power consumption reducing method of a CDMA communication apparatus comprises the steps of demodulating signals received by at least two antennas to thereby output reception signals, shifting phases of the reception signals every predetermined interval and then correlating the reception signals with respect to a predetermined data to thereby output correlation value data, detecting peaks from at least two correlation value data, comparing the peaks detected from at least the two correlation value data with each other to obtain a comparison result, and substantially stopping processing the signal received by at least one of said antennas based on the comparison result.
To achieve the above-described objects of the present invention, a CDMA receiving apparatus, comprises two reception systems for receiving signals, demodulating the received signals, and correlating the demodulated reception signals with respect to a predetermined data to thereby output a correlation value, and a control unit for substantially stopping operation of at least one of the plural reception systems based upon the correlation values outputted from the respective reception systems.